The threat to human health posed by antibiotic-resistant bacterial pathogens is of growing concern to medical practice. This study investigated the antibiotic sensitivity pattern of Salmonella typhi isolated from blood specimen. One hundred blood samples were collected from suspected typhoid fever patients in 31 Artillery Brigade Medical Centre, Minna, and were analyzed for S. typhi while antibiotic sensitivity testing was done Kirby-Bauer method. Sixty (60.0%) samples out of the total 100 were positive for bacterial growth. The organisms isolated 2 include Salmonella typhi; 45 (75.0%), Shigella; 6 (10.0%), E. coli; 3 (5.0%), Klebsiella; 3 (5.0%), Enterobacter; 2 (3.3%), and Citrobacter; 1 (1.7%). Result of the sensitivity test showed that the isolates were resistant to all the antibiotics; ceftriaxone, cefuroxime, amoxicillin, ampicillin, ciprofloxacin, and augmentin, which are the drug of choice routinely used in the study area for the treatment of typhoid fever. They were however sensitive to chloramphenicol and ofloxacin, which, unfortunately, are not used in this study area for the treatment of typhoid fever. There appear to be multiple drug resistant (MDR) strain of S. typhi in the study area. These may be as a result of overdependence or uncontrolled use of the few available antibiotics and/or inaccurate or inconclusive diagnosis resulting in the development and spread of resistant strains of S. typhi. The study, therefore, highlights the need for a strong collaboration between the physicians and the laboratory in the choice of antibiotics for the treatment of bacterial diseases in order to discourage the development of resistant strain of bacterial pathogen

A Madzu

A Momojimoh

B U Ezugwu

D Damisa

Jim P Buttery

N U Adabara

Z Hashiimu

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Hindawi Publishing Corporation
Advances in Preventive Medicine
Volume 2012, Article ID 875419, 4 pages
doi:10.1155/2012/875419
Clinical Study
The Prevalence and Antibiotic Susceptibility Pattern of
Salmonella typhi among Patients Attending a Military Hospital in
Minna, Nigeria
N. U. Adabara,1 B. U. Ezugwu,1 A. Momojimoh,1 A. Madzu,2 Z. Hashiimu,3 and D. Damisa1
1 Department of Microbiology, Federal University of Technology, PMB 65, Minna, Nigeria
2 31, Artillery Brigade Medical Centre, Minna 0098, Nigeria
3 Department of Microbiology, Faculty of Natural Sciences, University of Jos, Jos 2084, Nigeria
Correspondence should be addressed to N. U. Adabara, nasadabs@yahoo.com
Received 31 March 2012; Accepted 7 August 2012
Academic Editor: Jim P. Buttery
Copyright © 2012 N. U. Adabara et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The threat to human health posed by antibiotic-resistant bacterial pathogens is of growing concern to medical practice. This study
investigated the antibiotic sensitivity pattern of Salmonella typhi isolated from blood specimen. One hundred blood samples were
collected from suspected typhoid fever patients in 31 Artillery Brigade Medical Centre, Minna, and were analyzed for S. typhi while
antibiotic sensitivity testing was done Kirby-Bauer method. Sixty (60.0%) samples out of the total 100 were positive for bacterial
growth. The organisms isolated 2 include Salmonella typhi; 45 (75.0%), Shigella; 6 (10.0%), E. coli; 3 (5.0%), Klebsiella; 3 (5.0%),
Enterobacter; 2 (3.3%), and Citrobacter; 1 (1.7%). Result of the sensitivity test showed that the isolates were resistant to all the
antibiotics; ceftriaxone, cefuroxime, amoxicillin, ampicillin, ciprofloxacin, and augmentin, which are the drug of choice routinely
used in the study area for the treatment of typhoid fever. They were however sensitive to chloramphenicol and ofloxacin, which,
unfortunately, are not used in this study area for the treatment of typhoid fever. There appear to be multiple drug resistant (MDR)
strain of S. typhi in the study area. These may be as a result of overdependence or uncontrolled use of the few available antibiotics
and/or inaccurate or inconclusive diagnosis resulting in the development and spread of resistant strains of S. typhi. The study,
therefore, highlights the need for a strong collaboration between the physicians and the laboratory in the choice of antibiotics for
the treatment of bacterial diseases in order to discourage the development of resistant strain of bacterial pathogen.
1. Introduction
Typhoid fever (enteric fever) caused by the bacterium Sal-
monella enteric serovar typhi is an endemic disease in the
tropic and subtropic. The disease is systemic and is often
contracted by ingestion of food or water that is contaminated
with the pathogen usually from a feco-oral source. It may,
therefore, be reasonable to conclude that the occurrence
of typhoid fever is an indicator of poor personal and
environmental hygiene. The illness may be mild or severe but
sometimes fatal. It is encountered worldwide but is primarily
found in developing countries where sanitary conditions are
poor [1]. Typhoid fever is now uncommon in developed
countries where most occurrences are either acquired abroad
or imported by emigrants [2]. With an estimatedannual
incidence of 540 per 100,000 or about 17 million cases
worldwide [3], the disease is considered a major public health
problem. In tropical countries including Nigeria where the
disease is often encountered, they account for several cases of
morbidities and mortalities [4].
Enteric fever has continued to be a major health problem
despite the use of antibiotics and the development of newer
antibacterial drugs. The causative organism Salmonella typhi
has rapidly gained resistance to antibiotics like ampicillin,
ceftriaxone, and cotrimoxazole, and also to previously effica-
cious drugs like ciprofloxacin [5]. The emergence of antimi-
crobial resistance, especially the multidrug resistance to
ampicillin, chloramphenicol, and cotrimoxazole, has further
complicated the treatment and management of enteric fever
[6]. The resistance to well-known and trusted antimicrobial
agents is widely recognized as one of the greatest challenges
2 Advances in Preventive Medicine
that physicians face in the management of adult and pediatric
infections [7].
Salmonella typhi, particularly the multidrug resistant
(MDR) strain is relatively ubiquitous and is the cause of
many community endemic and epidemic typhoid fever in-
fections. MDR strain of S. typhi is of concern not only
because of its resistance to available antibiotics resulting in
high death rate but also because of its potential for epi-
demic outbreaks, which may be difficult to manage. The
consequence of such outbreak will no doubt be devastating
especially in developing countries where health facilities are
often inadequate.
It has been opined that the initial development of
resistance by S. typhi and most other bacterial pathogens
occurred as a result of indiscriminate use of antibacterial
drugs hence the need for caution in antibiotic prescription
and administration. Determining the antibiotic sensitivity
pattern of isolates is necessary since it will guide the phy-
sicians in making the right choice of drugs when treating
patients thus ensuring quick treatment of the infection
without aggravating the illness and preventing antibiotic
resistance.
This study investigated the antibiotic sensitivity pattern
of Salmonella typhi isolated from patients in Minna.
2. Materials and Methods
2.1. Study Area. The study area is 31 Artillery Brigade Medi-
cal Centre, Minna, Niger State. The hospital is located in the
Nigerian Army Cantonment situated at km 98, Suleja/Abuja
road, Minna.
2.2. Study Population. A total number of 100 suspected
typhoid fever patients aged from 1–50 years were screened
for S. typhi in this study. The subjects were all inhabitants
of the Cantonment comprising of military personnel and
civilians with a common source of drinking water. Subjects
were enlisted based on informed consent.
2.3. Collection of Blood Samples. Five milliliters of blood
was collected from each subject by venupuncture for the
detection of Salmonella typhi. The blood samples were
collected over a period of 30 days. Ten (10) samples were
collected on each visit to the hospital. Sample collection
was done using sterile disposable syringes and blood bottles
containing anticoagulant (EDTA). The samples were quickly
transported to the Microbiology Laboratory of the Federal
University of Technology, Minna, where the analysis was
done.
2.4. Preparation of Salmonella-Shigella Agar. Approximately
16 g of the dehydrated Salmonella-Shigella Agar was dis-
solved in 250 mL of distilled water in the preparation
of the growth medium. This is in agreement with the
manufacturer’s directive. The mixture was brought to boil
with frequent agitation until the agar has dissolved properly.
It was then allowed to cool down to 50◦C after which it was
dispensed into petri dishes and allowed to gel.
Table 1: Frequency of occurrence of Bacterial isolates.
Organisms isolated Frequency Percentage frequency (%)
Salmonella typhi 45 75.0
Shigella sp. 6 10.0
E. coli. 3 5.0
Klebsiella sp. 3 5.0
Enterobacter sp. 2 3.3
Citrobacter sp. 1 1.7
Total 60 100
2.5. Isolation of Bacteria. Blood samples were inoculated
into Salmonella-Shigella Agar (SSA) by streaking method
after which the plates were incubated at 37◦C for 24 hours.
Isolates from the primary cultures were subcultured into
fresh SSA medium to obtain pure isolates. Pure isolates were
inoculated in nutrient agar slant and stored at 5◦C for further
characterization and identification.
2.6. Characterization and Identification. Pure isolates ob-
tained on nutrient agar were identified and characterized
based on colonial morphology, cultural characteristics, Gram
stain reaction, and biochemical tests.
2.7. Antibiotic Sensitivity Testing. Antibiotic sensitivity test-
ing was done using Kirby-Bauer method on Mueller Hinton
Agar. 3.8 g of this agar was dispensed into a sterile conical
flask. One hundred milliliter (100 mL) of distilled water
was poured into the flask and stirred to dissolve the agar.
The mixture was autoclaved and then poured into petri
dishes. On gelling, the negative antibiotic sensitivity disk was
introduced using sterile forceps and then incubated for 24
hours at 37◦C.
3. Results
Out of the 100 samples investigated, 60 (60.0%) samples were
positive for bacterial growth. The result of the characteriza-
tion and identification of the isolates revealed that Salmonella
typhi had the highest frequency of occurrence with 45
(75.0%) isolates followed in descending order by Shigella 6
(10.0%), E. coli 3 (5.0%), Klebsiella 3 (5.0%), Enterobacter 2
(3.3%), and Citrobacter 1 (1.7%), respectively (Table 1).
3.1. Distribution of S. typhi Isolated from Subjects on the Basis
of Age. Out of the 45 samples that were positive for S. typhi.
The highest frequency of occurrence was found between the
ages of 1–10 years while 41–50 years had the least frequency
of occurrence (Table 2).
3.2. Result of Antibiotic Sensitivity Test. The result of the
in vitro antibiotic sensitivity test showed that isolates of S.
typhi were generally resistant to ceftriaxone, cefuroxime,
amoxicillin, ampicillin, ciprofloxacin, and augmentin which
are the drugs of choice routinely used in the study area for
the treatment of typhoid fever. They were, however, sensitive
to ofloxacin and chloramphenicol even though these two
Advances in Preventive Medicine 3
Table 2: Distribution of S. typhi isolated from subjects on the basis of age.
Age group No investigated No positive for S. typhi Frequency of (%)
1–10 30 20 44.46
11–20 20 8 17.76
21–30 25 7 15.56
31–40 15 7 15.56
41–50 10 3 6.76
Total 100 45 100%
Table 3: Measurement of zone of inhibition.
Disc code (antibiotic name) (S. typhi) Ave. diameter of zone of inhibition (mm) Sensitivity pattern
Ampicillin 2.5 R
Cefuroxime 5.5 R
Ceftriaxone 5.4 R
Chloramphenicol 17.3 S
Ciprofloxacin 6.5 R
Ofloxacin 15.2 S
Amoxicillin 3.5 R
Augmentin 5.2 R
Key: S: sensitive, I: intermediate, R: resistant.
antibiotics are no longer used for the treatment of typhoid
fever in the study area on account of adverse reactions
(Table 3).
Enterobacter, Citrobacter, Escherichia, Klebsiella and Shi-
gella were all resistant to the antibiotics except amoxicillin.
Shigella is weakly sensitive to ampicillin and strongly sensitive
to ciprofloxacin, both which are not active against S. typhi.
4. Discussion
The result of this study revealed a prevalence rate of 45.0%
for typhoid fever in the study area. This finding is similar to
the 46.0% prevalence rate earlier reported [8] in Tribhuvan
University Teaching Hospital, Nepal, India, both of which
agree with the position of the World Health Organization
[9] that the vast majority of typhoid fever cases occur in
Asia, Africa and Latin America where water borne diseases
are highly prevalent because of inadequate supply of potable
water to the public with concomitant poor environmental
and personal hygiene.
The result also revealed a high prevalence of typhoid fever
(44.4%) among children within the age group (1–10) years
which is also in agreement with an earlier report of 43.9%
prevalence rate [10] in Cebu City, India. It is reasoned that
children form the most vulnerable group in environments
where inadequate water supply and poor environmental
hygiene are problems because of their high level of ignorance.
They are usually quick to satisfy their thirst irrespective of the
water source especially if the water is apparently clean and
without color.
There was no significant difference in clinical presenta-
tion shown by the subjects as against what has been reported
[11] in the editorial commentary of the February edition of
Clinical Infectious Diseases from Uganda where intestinal
perforation was observed among children aged between 1–
5 years. In the study area, access to medical care is free which
makes it easy for subjects to seek medical attention without
the needless delay that often account for the pathologic
damages seen in cases where access to healthcare services is
constrained such as intestinal perforation.
High level of antibiotic resistance by isolates was
observed to the routinely used antibiotics in the study
area.this in agreement with the earlier report of a worldwide
occurrence of multidrug resistance strains of S. typhi. This
development as observed may be traceable to wrong and
inaccurate diagnosis and abusive use of the available antibi-
otics resulting in the development and spread of multidrug
resistant strains of S. typhi.
Malaria is endemic in Africa and the area under study
is not an exception especially during wet season when
the population of mosquito vectors increases as a result
of stagnant waters and bushy surroundings. The isolation
of nontyphoidal bacterial agents from suspected typhoid
patients calls for a review of the present approach to the
diagnosis of typhoid in the study area. Improper diagnosis
leads to the misuse of antibiotics by physicians which in turn
lead to the development of resistance by organisms.
The result of this study indicates that chloramphenicol
and ofloxacin (which are no longer routinely used for the
treatment of typhoid fever in the study area) have proved to
be active against this isolates even though they were resistant
to the commonly prescribed drugs. This observation that an
organism that is previously resistant to a particular antibiotic
may become susceptible if treatment with the antibiotic is
suspended for a long time supporting what has been reported
earlier [12] is interesting because of its obvious implication
for public health management. However, more studies are
recommended in this in this regard.
4 Advances in Preventive Medicine
5. Conclusion
The result of this study has further accentuated the growing
concern about the presence of and the spread of multidrug
resistant S. typhi thereby underscoring the need for rational
application of antibiotics and other necessary interventions
that will help to control the menace of antibiotic resistance.
Provision of potable water, accurate laboratory diagnosis,
public education, and so forth, are, therefore, recommended.
Surveillance programs to monitor antimicrobial resistance
patterns in other parts of the state and the entire country in
general are also recommended.
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Clinical Study The Prevalence and Antibiotic Susceptibility Pattern of Salmonella typhi among Patients Attending a Military Hospital in Minna, Nigeria

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Clinical Study The Prevalence and Antibiotic Susceptibility Pattern of Salmonella typhi among Patients Attending a Military Hospital in Minna, Nigeria

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